2. Acknowledgements
Thai Cochrane Network
Prof. Malinee Laopaiboon

3. Steps of conducting a Cochrane review
1. Define review question
2. Plan eligibility criteria
3. Plan methods
4. Search for studies
5. Selecting studies
6. Collecting data
7. Assess study for risk of bias
8. Analyse and present results
9. Interpret results and form conclusions
10. Improve and update review
Register title
Publish protocol
Publish review
Publish update

4. Data extraction and management
Selection of studies
Data extraction and management

5. Identifying multiple reports from the same study
Author names
Location and setting
Specific details of the interventions
Numbers of participants and baseline data
Date and duration of the study
Registration no.
7.2.2  Identifying multiple reports from the same study
Duplicate publication can introduce substantial biases if studies are inadvertently included more than once in a meta-analysis (Tramèr 1997). Duplicate publication can take various forms, ranging from identical manuscripts to reports describing different numbers of participants and different outcomes (von Elm 2004). It can be difficult to detect duplicate publication, and some ‘detective work’ by the review authors may be required.
Some of the most useful criteria for comparing reports are:
Author names (most duplicate reports have authors in common, although it is not always the case);
Location and setting (particularly if institutions, such as hospitals, are named);
Specific details of the interventions (e.g. dose, frequency);
Numbers of participants and baseline data;
Date and duration of the study (which can also clarify whether different sample sizes are due to different periods of recruitment).
Where uncertainties remain after considering these and other factors, it may be necessary to correspond with the authors of the reports.

6. Minimising bias in selection
selecting studies involves judgement, and is highly influential on the outcomes of the review
compare each record with pre-specified eligibility criteria
- written summary or checklist may be helpful
two authors should independently select studies
- discussion may identify issues for clarification or gaps in your eligibility criteria
- pilot selection on a few papers first
- disagreements can usually be resolved by discussion or referral to a third author

7. What to include in your protocol
whether two authors will independently assess studies
process of assessment (e.g. abstracts, full text)
how disagreements will be managed
any other methods used

8. Kietpeerakool C, Supoken A, Laopaiboon M, Lumbiganon P
Effectiveness of tranexamic acid in reducing blood loss during cytoreductive surgery for advanced ovarian cancer (Protocol)
Kietpeerakool C, Supoken A, Laopaiboon M, Lumbiganon P

11. What about studies with no usable data?
Studies must be included in the review if they meet your criteria
- results reported in non- standard ways should still be reported in the review
- studies that do not report outcomes of interest may have measured them – beware of selective reporting
- studies that did not measure outcomes of interest may only be excluded if outcomes were pre- specified as part of your eligibility criteria

12. Process for selecting studies
Merge search results
Examine titles and abstracts
Examine full text reports
Correspond with investigators
Make final decisions
7.2.3  A typical process for selecting studies
A typical process for selecting studies for inclusion in a review is as follows (the process should be detailed in the protocol for the review).
Merge search results using reference management software, and remove duplicate records of the same report (see Chapter 6, Section 6.5);
Examine titles and abstracts to remove obviously irrelevant reports (authors should generally be over-inclusive at this stage);
Retrieve full text of the potentially relevant reports;
Link together multiple reports of the same study (see Section 7.2.2);
Examine full text reports for compliance of studies with eligibility criteria;
Correspond with investigators, where appropriate, to clarify study eligibility (it may be appropriate to request further information, such as missing results, at the same time);
Make final decisions on study inclusion and proceed to data collection.

13. Selecting studies (I) Merge search results from resource MEDLINE
EMBASE………..
Search results
merge

14. Selecting studies (II)
Remove duplicate records
Search results 

15. Selecting studies (III)
Examine title and abstracts 
Exclude obviously irrelevant reports
Title…………
Abstract……
Title……
Abstract……
Potentially relevant reports
Title…………
Abstract……
Title…………
Abstract……
Title…………
Abstract……
should be done independently by at least two review authors

16. Selecting studies (IV)
Retrieve and examine full text reports
Search results
Title…………
Abstract……
Title…………
Abstract……
Retrieve full text and examine
Title…………
Abstract……
should be done independently by at least two review authors

17. Selecting studies (V)
Compare selected studies done by two independent reviewers
Search results
Title…………… Abstract……
2nd review author
Judgment
exclude
Search results
Title…………… Abstract……
1st review author
Judgment
exclude
Address reasons for study exclusion
How disagreements are handle?

18. Selecting studies (VI)
Search results
Title…………… Abstract……
1st+ 2nd review author
Judgment
exclude
Correspond with investigators
Make final decisions

19. Selecting ‘excluded studies’
By listing such studies as excluded and giving the primary reason for exclusion.
The list of excluded studies should be as brief as possible.
7.2.5  Selecting ‘excluded studies’
A Cochrane review includes a list of excluded studies, detailing any studies that a reader might plausibly expect to see among the included studies. This covers all studies that may on the surface appear to meet the eligibility criteria but on further inspection do not, and also those that do not meet all of the criteria but are well known and likely to be thought relevant by some readers. By listing such studies as excluded and giving the primary reason for exclusion, the review authors can show that consideration has been given to these studies. The list of excluded studies should be as brief as possible. It should not list all of the reports that were identified by a comprehensive search. It should not list studies that obviously do not fulfil the entry criteria for the review as listed under ‘Types of studies’, ‘Types of participants’, and ‘Types of interventions’, and in particular should not list studies that are obviously not randomized if the review includes only randomized trials.

21. The PRISMA Flow Diagram
The flow diagram depicts the flow of information through the different phases of a systematic review.
It maps out the number of records identified, included and excluded, and the reasons for exclusions.

23. PRISMA 2009 Flow Diagram

24. Data extraction and management

25. What data should you collect?

26. Key elements of data extraction form (I) (Table 7.3a)
Part 1: Source
• Title of Review
• Reviewer
• Study ID
• Citation and contact details

27. Key elements of data extraction form (II)
Part 2: Eligibility information
This part is used to complete the “Characteristics of included studies table” Components: Methods
Participants
Interventions
Outcomes
Help in making decision of study exclusion

28. Key elements of data extraction form (III)
Part 3 : Study details
Methods
Assessment risk of bias
Participants
Information of each intervention
Outcome information
Results
Other information e.g. source of funding

29. Collecting outcome data
Focus on those outcomes specified in your protocol
- Be open to unexpected finding e.g. adverse effects
Measures used
Definition (diagnostic criteria, threshold)
Timing
Unit of measurement
For scales (upper and lower limits, direction of benefit)

30. Collecting outcome data (cont.)
Numerical results
May be in many formats – conversion may be required
Collect whatever is available
no. participants for each outcome & time point

31. Dichotomous outcomes

32. Data in many formats Outcome Reported as Trials
Volume transfused (mls)
Mean and SEM
Mean and SD
Mean and something in brackets
Two unlabelled numbers e.g. x(y)
Bar chart showing mean per person year 4 2 1
Units transfused
Mean only
Total in each group
Volume adjusted for patient mass (mls/kg)
Patient who had a transfusion
Number of patients 3
Not reported

33. Putting into practice
Data collection forms

34. Rationale for data collection form
Linked directly to
Review question
Criteria for assessing
eligibility of study

35. Data collection forms Organise all the information you need
- reminds what to collect
- records what was not reported in the study
- records the decision that make about each study
Must be tailored to your review
- adapt from a good example
Paper or electronic

37. Minimising bias in data collection
Two authors should independently collect study characteristics and outcome data
Reduces error
Checks agreement on subjective judgment and interpretations
Complementary disciplines (methodologist/ topic area specialist)
Resolving disagreements
By discussion
If not, refer to a third author
Pilot data collection process
Include each person assisting
Check criteria are consistently applied
May need to revise form or instructions

38. Contacting study authors
To obtain unreported data or confirm unclear data
- Missing outcomes, unclear risk of bias
Finding contact details
Check the study reports
Check PubMed for recent publications
Check Google for current staff profiles
Save all your queries for one request
Be clear about what you need
Avoid sounding critical
Ask for descriptions rather than yes/ no answers

39. Managing data Can enter data directly from form to RevMan
May need to consider intermediate steps
e.g. Excel spreadsheet
Group studies by comparison & outcomes measured
Calculations to convert into required statistics
Don’t forget to check your final results against those reported in the study

40. How disagreement are handled?
Use one author’s (paper) data collection form and record changes after consensus in a different ink color
Use a separate (paper) form for consensus data
Enter consensus data onto an electronic form

41. What include in your protocol
Data categories to be collected
Two authors will independently extract data
Piloting and use of instructions for data collection form
How disagreements will be managed
Processes for managing missing data

42. Kietpeerakool C, Supoken A, Laopaiboon M, Lumbiganon P
Effectiveness of tranexamic acid in reducing blood loss during cytoreductive surgery for advanced ovarian cancer (Protocol)
Kietpeerakool C, Supoken A, Laopaiboon M, Lumbiganon P